Yes you can, I did it 1 month ago (from MG to Azurite Black). At this time only the frozen colours were not available.

But if I understand correct, you went from no individual options to an individual colour? It might be different if you already had an individual colour (when I chose individual interior I was 'locked' the next day in the system - the individual choice locks an individual slot - whereas if you didn't have an individual slot already you wouldn't have had the individual spot 'locked' at the time you choose and individual option).

Regardless, I understand even then they can call and potentially change something.

My order is only a normal 4 series, but I suspect M4 individual options may be similar.

Also I ordered mid March, told May delivery and most recently was told production week 26 with delivery at the beginning of July (to Poland, so not too far to go). We'll see - theoretically they should be building this week and hopefully not drinking beer in the evenings.